The objective of these studies is to evaluate factors concerned with regulation of the hypothalamus and pituitary gland in human reproductive events and the possible influence of prolactin on these regulatory phenomena. Studies will be performed in hyperprolactinemic women with and without demonstrable pituitary adenomas to assess 1) pituitary sensitivity to hypothalamic gonadotropin releasing hormone and estradiol as modified by altered prolactin levels, 2) positive feedback of estradiol on gonadotropins in the presence of elevated prolactin, 3) effects of development of hyperprolactinemia on temporal changes in pituitary and ovarian hormones, 4) morphologic characteristics of, secretory capacity of, and influence of dopamine on, prolactin producing pituitary tumors, 5) the possible association of antecedent use of oral contraceptives and the development of pituitary microadenomas, and 6) the relative efficacy of microsurgical resection, 2-Bromergocryptine or no therapy in the management of pituitary microadenomas.